mirror of https://github.com/status-im/consul.git
Merge pull request #13999 from hashicorp/docs/improve-dns-lookup-variable-consistency
docs: improve consistency of DNS lookup variables
This commit is contained in:
Jared Kirschner
GitHub
commit
eb645453d6
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@ -52,7 +52,7 @@ There are fundamentally two types of queries: node lookups and service lookups.
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A node lookup, a simple query for the address of a named node, looks like this:
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```text
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<node>.node[.datacenter].<domain>
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<node>.node[.<datacenter>].<domain>
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```
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For example, if we have a `foo` node with default settings, we could
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@ -79,16 +79,16 @@ $ dig @127.0.0.1 -p 8600 foo.node.consul ANY
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;; WARNING: recursion requested but not available
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;; QUESTION SECTION:
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;foo.node.consul. IN ANY
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;foo.node.consul. IN ANY
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;; ANSWER SECTION:
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foo.node.consul. 0 IN A 10.1.10.12
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foo.node.consul. 0 IN TXT "meta_key=meta_value"
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foo.node.consul. 0 IN TXT "value only"
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foo.node.consul. 0 IN A 10.1.10.12
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foo.node.consul. 0 IN TXT "meta_key=meta_value"
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foo.node.consul. 0 IN TXT "value only"
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;; AUTHORITY SECTION:
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consul. 0 IN SOA ns.consul. postmaster.consul. 1392836399 3600 600 86400 0
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consul. 0 IN SOA ns.consul. postmaster.consul. 1392836399 3600 600 86400 0
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```
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By default the TXT records value will match the node's metadata key-value
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@ -121,7 +121,7 @@ it is recommended to use the HTTP API to retrieve the list of nodes.
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The format of a standard service lookup is:
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```text
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[tag.]<service>.service[.datacenter].<domain>
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[<tag>.]<service>.service[.<datacenter>].<domain>
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```
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The `tag` is optional, and, as with node lookups, the `datacenter` is as
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@ -157,26 +157,37 @@ $ dig @127.0.0.1 -p 8600 consul.service.consul SRV
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;; WARNING: recursion requested but not available
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;; QUESTION SECTION:
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;consul.service.consul. IN SRV
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;consul.service.consul. IN SRV
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;; ANSWER SECTION:
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consul.service.consul. 0 IN SRV 1 1 8300 foobar.node.dc1.consul.
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consul.service.consul. 0 IN SRV 1 1 8300 foobar.node.dc1.consul.
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;; ADDITIONAL SECTION:
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foobar.node.dc1.consul. 0 IN A 10.1.10.12
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foobar.node.dc1.consul. 0 IN A 10.1.10.12
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```
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### RFC 2782 Lookup
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The format for RFC 2782 SRV lookups is:
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Valid formats for RFC 2782 SRV lookups depend on
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whether you want to filter results based on a service tag:
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_<service>._<protocol>[.service][.datacenter][.domain]
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- No filtering on service tag
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Per [RFC 2782](https://tools.ietf.org/html/rfc2782), SRV queries should use
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underscores, `_`, as a prefix to the `service` and `protocol` values in a query to
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prevent DNS collisions. The `protocol` value can be any of the tags for a
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service. If the service has no tags, `tcp` should be used. If `tcp`
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is specified as the protocol, the query will not perform any tag filtering.
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```text
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_<service>._tcp[.service][.<datacenter>].<domain>
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```
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- Filtering on service tag specified in the RFC 2782 protocol field
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```text
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_<service>._<tag>[.service][.<datacenter>].<domain>
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```
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Per [RFC 2782](https://tools.ietf.org/html/rfc2782), SRV queries must
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prepend an underscore (`_`) to the `service` and `protocol` values in a query to
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prevent DNS collisions.
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To perform no tag-based filtering, specify `tcp` in the RFC 2782 protocol field.
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To filter results on a service tag, specify the tag in the RFC 2782 protocol field.
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Other than the query format and default `tcp` protocol/tag value, the behavior
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of the RFC style lookup is the same as the standard style of lookup.
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@ -196,13 +207,13 @@ $ dig @127.0.0.1 -p 8600 _rabbitmq._amqp.service.consul SRV
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;; WARNING: recursion requested but not available
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;; QUESTION SECTION:
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;_rabbitmq._amqp.service.consul. IN SRV
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;_rabbitmq._amqp.service.consul. IN SRV
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;; ANSWER SECTION:
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_rabbitmq._amqp.service.consul. 0 IN SRV 1 1 5672 rabbitmq.node1.dc1.consul.
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_rabbitmq._amqp.service.consul. 0 IN SRV 1 1 5672 rabbitmq.node1.dc1.consul.
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;; ADDITIONAL SECTION:
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rabbitmq.node1.dc1.consul. 0 IN A 10.1.11.20
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rabbitmq.node1.dc1.consul. 0 IN A 10.1.11.20
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```
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Again, note that the SRV record returns the port of the service as well as its IP.
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@ -328,7 +339,7 @@ $ echo -n "20010db800010002cafe000000001337" | perl -ne 'printf join(":", unpack
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The format of a prepared query lookup is:
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```text
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<query or name>.query[.datacenter].<domain>
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<query or name>.query[.<datacenter>].<domain>
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```
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The `datacenter` is optional, and if not provided, the datacenter of this Consul
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@ -376,7 +387,7 @@ If you need more complex behavior, please use the
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To find the unique virtual IP allocated for a service:
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```text
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<service>.virtual[.peer].<domain>
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<service>.virtual[.<peer>].<domain>
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```
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This will return the unique virtual IP for any [Connect-capable](/docs/connect)
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@ -439,14 +450,14 @@ The following responses are returned:
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```
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;; QUESTION SECTION:
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;consul.service.test-domain. IN SRV
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;consul.service.test-domain. IN SRV
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;; ANSWER SECTION:
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consul.service.test-domain. 0 IN SRV 1 1 8300 machine.node.dc1.test-domain.
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consul.service.test-domain. 0 IN SRV 1 1 8300 machine.node.dc1.test-domain.
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;; ADDITIONAL SECTION:
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machine.node.dc1.test-domain. 0 IN A 127.0.0.1
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machine.node.dc1.test-domain. 0 IN TXT "consul-network-segment="
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machine.node.dc1.test-domain. 0 IN A 127.0.0.1
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machine.node.dc1.test-domain. 0 IN TXT "consul-network-segment="
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```
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-> **PTR queries:** Responses to PTR queries (`<ip>.in-addr.arpa.`) will always use the
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@ -479,7 +490,7 @@ resolve services within the `default` namespace and partition. However, for reso
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services from other namespaces or partitions the following form can be used:
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```text
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[tag.]<service>.service.<namespace>.ns.<partition>.ap.<datacenter>.dc.<domain>
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[<tag>.]<service>.service.<namespace>.ns.<partition>.ap.<datacenter>.dc.<domain>
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```
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This sequence is the canonical naming convention of a Consul Enterprise service. At least two of the following
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@ -491,14 +502,14 @@ fields must be present:
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For imported lookups, only the namespace and peer need to be specified as the partition can be inferred from the peering:
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```text
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<service>.virtual[.namespace][.peer].<domain>
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<service>.virtual[.<namespace>].<peer>.<domain>
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```
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For node lookups, only the partition and datacenter need to be specified as nodes cannot be
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namespaced.
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```text
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[tag.]<node>.node.<partition>.ap.<datacenter>.dc.<domain>
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[<tag>.]<node>.node.<partition>.ap.<datacenter>.dc.<domain>
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```
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## DNS with ACLs
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